Summary:
* Some existing commentary and motivation around my atomic wrappers in atomic.h was based on a misreading of documentation. seq_cst *is* a safe substitute for acq_rel in all cases. I still like having a distinct type for RelaxedAtomic (as folly does) and a wrapper also for other cases to avoid readability traps like implicit conversion and implicit memory order. This PR is only comment changes and renaming.
* Create a blog post about bit fields API to help with lock-free (and low-lock) programming.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/14213
Test Plan: esiting tests
Reviewed By: xingbowang
Differential Revision: D89971581
Pulled By: pdillinger
fbshipit-source-id: 9bd1181d692258d668189c2da8bd0e5d98fd6230
387cb4aae7